Thepupose of this study was to grasp the social cognitive function of older adults in whom cognitive decline is difficult to recognize from an intelligence test score and communication ability. The ultimate objective was enable prediction of MCI and mild dementia. Care receivers who maintained communication ability were classified into a cognitive function maintaining group, and deteriorating group and caregiver groups were added. The false-belief-task that had been used for scaling the theory of mind function was conducted. In study 1, the false-belief-task for an infant was conducted in 13 people in the maintaining group, 29 people in the deteriorating group, and 11people in the caregiver group; no significant difference was recognized between the groups. Based on the results of study 1, the false-belief-task for older adults that I adapted was conducted in study 2 in, 49 people in the maintaining group, 24 people in the deteriorating group, and 11 people in the caregiver group. As the results, in the false-belief-task for older adults，“saving appearances behavior，''which was recognized as a characteristic of MCI and mild dementia patients,was clearly observed. However, compared to the case of false-belief tasks for children, the correct answer rate decreased considerably for the group of those whose cognitive functions were declining but whose communication abilities were not, and that left room for reconsideration of cognitive load.